Process for recycling polyolefin blend composition using an ethylene copolymer compatibilizing agent

ABSTRACT

A process is provided for preparing polymer composites from compositions comprising i) a polyolefin, ii) a polymer selected from the group consisting of polymers having hydroxyl groups and polymers having amino groups and iii) a polar ethylene copolymer having copolymerized units selected from the group consisting of C 4 -C 8  unsaturated anhydrides, monoesters of C 4 -C 8  unsaturated acids having at least two carboxylic acid groups, diesters of C 4 -C 8  unsaturated acids having at least two carboxylic acid groups and mixtures thereof. The process is suitable for use with recycle streams that contain polymeric materials that are laminates or composites of dissimilar polymers.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of U.S. patent application Ser. No.11/413,553, filed Apr. 28, 2006, the entire contents being incorporatedherein by reference.

FIELD OF THE INVENTION

This invention relates to a method for recycling thermoplastic polymers.The invention also relates to polymer blend compositions that are easilyprocessable and to articles prepared from such compositions.

BACKGROUND OF THE INVENTION

Many consumer and industrial products are formed from thermoplasticcomposite or laminate materials. Such materials include for examplecontainer walls and countertop materials. For a variety of aesthetic andfunctional reasons the composites or laminates may be composed of quitedissimilar polymers. For example, composite materials are often blendsof two or more polymers that are present in discrete phases within thepolymer matrix, due to the differing chemical properties of eachpolymeric component. Laminated materials often are designed to haveparticular barrier properties and contain plies made from dissimilarpolymers. The polymeric materials of the various layers then act totransmit or prevent transmission of certain gases in a controlledmanner. For example, a container lid or a fuel tank wall may be alaminated material that contains a polar polymer and a non-polar polymerin separate layers.

Some commonly used polymers that are present in laminated or compositematerials include polyamides, polyolefins, polyesters and ethylenecopolymers. Among this latter group are ethylene copolymers having polarcomonomers, such as ethylene vinyl alcohol copolymers, ethylene acrylicacid copolymers and ethylene methacrylic acid copolymers. Recyclingprocesses have the potential to convert such laminated or compositematerials into useful raw materials, but in many cases the basicincompatibility of the polymers in the recyclable product leads toproduction of non-homogeneous blends that have unacceptable physicalproperties. One solution to this problem is the use of additives thatcompatibilize dissimilar polymers. For example, in U.S. Pat. No.6,294,602 a process for recycling a mixture of ethylene vinyl alcoholcopolymer and a thermoplastic resin using a compatibilizer that is amixture of a polyamide resin and an ethylene-unsaturated carboxylic acidrandom copolymer or its metal salt is disclosed. Other compatibilizersare disclosed in K. Hausmann, “Compatibilizers, Polymeric (Recycling ofMultilayer Structures)”, Polymeric Materials Encyclopedia, CRC Press,NY, 1996, vol. 2, pp. 1364-1377.

Maleated polymers are a useful class of compatibilizing agents andtoughening agents for thermoplastic polymers. Such polymers includemaleic anhydride-grafted polyolefins and ethylene copolymers havingcopolymerized monomer units of maleic acid, maleic acid esters or maleicanhydride. For example, U.S. Pat. No. 5,179,164 discloses moldingcompositions comprising polypropylenes, polyamides and ethylenecopolymers grafted with maleic anhydride. PCT Published Application No.WO 98/41576 discloses toughened polyamides that are blends of ultrahighdensity polyethylene, polyamide and maleic anhydride graft copolymers.In addition, U.S. Pat. Nos. 4,174,358 and 5,408,000 and PCT PublishedApplication No. WO 03/099930A1 disclose various impact modifiers forpolyamides that include maleated polymers.

Maleic anhydride grafted polyolefins are generally prepared on acommercial scale by grafting maleic anhydride onto a polymeric backbonematerial, such as polyethylene, polypropylene,styrene-ethylene-butene-styrene triblock copolymer or polybutadiene.Maleated compatibilizers of this type include, e.g. Fusabond® MB 226DEand Fusabond® MD 353D adhesive resins, available from E. I. du Pont deNemours and Company. Another class of maleated compatibilizers includesethylene dipolymers and higher order copolymers that containcopolymerized units of e.g. maleic acid.

Although maleated polymers have been used as compatibilizers for variousresins, their potential as additives in recycling operations has notbeen fully utilized and optimized. It would be desirable to have aprocess available that makes more effective use of this class ofcompatibilizing agents in recycling processes. In addition, it would beuseful to have a process available that could more effectivelycompatibilize dissimilar polymers made from virgin materials.Compositions produced by such processes would be economical rawmaterials for fabricating consumer and industrial goods.

SUMMARY OF THE INVENTION

The present invention is directed to a process for preparing a polymercomposite comprising the steps of

-   -   A. forming a composition by combining        -   1. a polymer blend comprising            -   a. a first polymer selected from the group consisting of                polyethylenes and copolymers of ethylene and a C₃-C₁₀                alpha-olefin; and            -   b. a second polymer selected from the group consisting                of polymers having hydroxyl groups and polymers having                amino groups;            -   wherein said polymer blend has a moisture content                greater than 250 ppm water, based on the total weight of                said first and second polymers; and        -   2. a third polymer that is a polar copolymer produced by a            high pressure random copolymerization process, said polar            copolymer comprising copolymerized units of ethylene and            from about 3 wt. % to about 25 wt. %, based on the weight of            the polar copolymer, of a comonomer selected from the group            consisting of C₄-C₈ unsaturated anhydrides, monoesters of            C₄-C₈ unsaturated acids having at least two carboxylic acid            groups, diesters of C₄-C₈ unsaturated acids having at least            two carboxylic acid groups and mixtures thereof;        -   wherein said composition comprises, based on the total            weight of said first, second and third polymers, 55-98 wt. %            of said first polymer, 2-45 wt. % of said second polymer and            0.1-10 wt. % of said third polymer;    -   B. subjecting said composition to high shear mixing to form a        polymer composite that is a homogeneous blend; and    -   C. recovering said polymer composite.

The invention is further directed to an easily processable compositionprepared by combining:

-   -   A. a polymer blend comprising        -   1. a first polymer selected from the group consisting of            polyethylenes and copolymers of ethylene and a C₃-C₁₀            alpha-olefin; and        -   2. a second polymer selected from the group consisting of            polymers having hydroxyl groups and polymers having amino            groups;        -   wherein said polymer blend has a moisture content greater            than 250 ppm water, based on the total weight of said first            and second polymers; and    -   B. a third polymer that is a polar copolymer produced by a high        pressure random copolymerization process, said polar copolymer        comprising copolymerized units of ethylene and from about 3 wt.        % to about 25 wt. %, based on the weight of the polar copolymer,        of a comonomer selected from the group consisting of C₄-C₈        unsaturated anhydrides, monoesters of C₄-C₈ unsaturated acids        having at least two carboxylic acid groups, diesters of C₄-C₈        unsaturated acids having at least two carboxylic acid groups and        mixtures thereof;        wherein said processable composition comprises, based on the        total weight of said first, second and third polymers, 55-98 wt.        % of said first polymer, 2-45 wt. % of said second polymer and        0.1-10 wt. % of said third polymer.

The invention is also directed to a process for preparing a shapedarticle from a composite material which comprises the steps of

-   -   A. preparing a composite material by a process comprising the        steps of        -   1. forming a composition by combining            -   a. a polymer blend comprising                -   (1) a first polymer selected from the group                    consisting of polyethylenes and copolymers of                    ethylene and a C₃-C₁₀ alpha-olefin; and                -   (2) a second polymer selected from the group                    consisting of polymers having hydroxyl groups and                    polymers having amino groups;            -   wherein said polymer blend has a moisture content                greater than 250 ppm water, based on the total weight of                said first and second polymers; and            -   b. a third polymer that is a polar copolymer produced by                a high pressure random copolymerization process, said                polar copolymer comprising copolymerized units of                ethylene and from about 3 wt. % to about 25 wt. %, based                on the weight of the polar copolymer, of a comonomer                selected from the group consisting of C₄-C₈ unsaturated                anhydrides, monoesters of C₄-C₈ unsaturated acids having                at least two carboxylic acid groups, diesters of C₄-C₈                unsaturated acids having at least two carboxylic acid                groups and mixtures thereof;            -   wherein said composition comprises, based on the total                weight of said first, second and third polymers, 55-98                wt. % of said first polymer, 2-45 wt. % of said second                polymer and 0.1-10 wt. % of said third polymer; and        -   2. subjecting said composition to high shear mixing to form            a homogeneous composite material; and    -   B. forming said composite material into a shaped article.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a process for preparing polymercomposite compositions that are useful as raw materials for moldedgoods. The process is particularly suited for preparing composites thatare homogeneous polymer blend compositions from recycle streams, wherethe recyclable material consists of articles and compositions that havedissimilar polymeric components. By homogeneous blend is meant a blendthat is composed of either a continuous phase or is composed of two ormore discontinuous phases where the particle size of the largest domainof the minor phase is no more than 6 times the average particle size ofthe minor phase domains as measured in a transmission electronmicrograph image. In general, the process comprises the steps ofproviding a particular polymer blend composition having a suitablemoisture content, mixing the blend with a random copolymer to form aneasily processable composition and mixing the composition underconditions of high shear to form a compatibilized mixture. Due to thecomposition and steps of the process the compatibilized mixture is acomposite that is a homogeneous blend. The process is particularlyuseful in recycling operations, but may also be used with virgin polymermaterials.

The easily processable composition comprises three polymeric componentsand has a particular moisture content. The first polymer component is apolyethylene or a copolymer of ethylene and a C₃-C₁₀ alpha-olefin.“Copolymer”, as the term is used herein, has its conventional meaningknown to one of ordinary skill in the art to be a polymer formed by thecopolymerization of two or more monomers to yield a single polymer.Copolymers include dipolymers, terpolymers and higher order copolymers.

Polyethylenes suitable for use in the process of the invention may befor example, high density polyethylenes, low density polyethylenes,medium density polyethylenes or ultrahigh density polyethylenes, any ofwhich may be branched or unbranched. These polymers may be prepared byany process known in the art, among which are high pressure free radicalpolymerization processes and low pressure catalytic processes such asZiegler-Natta catalysis or catalysis with metallocene catalyst systems,for example those processes disclosed in U.S. Pat. Nos. 5,272,236 and5,278,272.

The ethylene copolymers may be thermoplastic or elastomeric ethylenecopolymers of ethylene with one or more comonomers selected frompropylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, and otherC₃-C₂₀ alpha-olefins. Thermoplastic ethylene alpha-olefin polymersinclude the class known as linear low density polyethylenes.Particularly useful examples include copolymers of ethylene and at leastone ethylenically unsaturated monomer selected from the group consistingof C₃-C₈ alpha monoolefins, Specific examples of these polymers arecopolymers of ethylene with propylene, butene, 3-methyl-1-pentene,hexene, or octene. Preferred olefin polymers are polyethylene andcopolymers of ethylene and C₄-C₈ alpha-olefins, such as ethylene butenecopolymers and ethylene octene copolymers. The olefin polymers havenumber average molecular weights within the range of 1,000 to 300,000,preferably from 50,000 to 300,000. Commercially available polymersinclude Sclair® polyethylene resins available from Nova Chemicals Corp.and Engage® polyolefin elastomers available from The Dow Chemical Co.Preferably, the first polymer component is a thermoplastic polymer thatcan be processed in the melt at temperatures below 220° C. Preferably,the polymer is a substantially linear ethylene polymer, such as thosedescribed in U.S. Pat. No. 5,272,236; U.S. Pat. No. 5,278,272, U.S. Pat.No. 5,507,475, U.S. Pat. No. 5,264,405, and U.S. Pat. No. 5,240,894.

Copolymers of the EPDM class, which are elastomeric copolymers ofethylene, propylene, and a diene may also be used in the process of theinvention. These copolymers can be terpolymers, tetrapolymers or higherorder copolymer elastomers of the ethylene/propylene/diene type and arecopolymers of ethylene, propylene and at least one non-conjugated diene.They may, in addition, contain a minor amount, generally up to 10 weightpercent, of at least one other diene or triene copolymerized monomerhaving copolymerizable double bonds. Non-conjugated dienes commonly usedas comonomers in EPDM terpolymers include 1,4-hexadiene;2-methyl-1,5-hexadiene; vinyl norbornene;8-methyl-4-ethylidene-1,7-octadiene; 1,9-octadecadiene;dicyclopentadiene; tricyclopentadiene; 5-ethylidene-2-norbornene; or5-methylene-2-norbornene. Preferred dienes having one reactive doublebond are 1,4-hexadiene, dicyclopentadiene and ethylidene norbornene.Non-conjugated dienes commonly used as an additional monomer in EPDMtetrapolymers include norbornadiene; 1,4-pentadiene; 1,5-hexadiene;1,7-octadiene; 1,2-heneicosadiene; or 5-(5-hexenyl)-2-norbornene,preferably norbornadiene. These polymers are generally produced bypolymerization in the presence of Ziegler-Natta catalysts or bypolymerization in the presence of metallocene catalysts. Preparativetechniques for ethylene alpha-olefin elastomers prepared in the presenceof metallocene catalysts may be found in U.S. Pat. Nos. 5,278,272 and5,272,236. Typical EPDM elastomers are commercially available as Nordel®hydrocarbon rubbers from The Dow Chemical Company.

The second polymer component in the blends useful in the process of theinvention is a thermoplastic resin that contains hydroxyl groups oramino groups. Examples of such resins include ethylene vinyl alcohol(EVOH), nylon 6 and nylon 6,6. Of the hydroxyl group containingpolymers, EVOH is preferred because of its ready availability.

EVOH generally has an ethylene content of between about 15 mole percentto about 60 mole percent, more preferably between about 27 to about 44mole percent. EVOH generally has a density ranging from between about1.12 g/cm³ to about 1.20 gm/cm³ and a melting temperature ranging frombetween about 142° C. and 191° C. The polymer can be prepared by knownpreparative techniques or can be obtained from commercial sources. It isprepared by saponifying or hydrolyzing ethylene vinyl acetatecopolymers. The degree of hydrolysis is preferably from about 50 to 100mole percent, more preferably from about 85 to 100 mole percent. Inaddition, the weight average molecular weight of the EVOH component,calculated from the degree of polymerization and the molecular weight ofthe repeating unit, may be within the range of about 5,000 M_(w) toabout 300,000 M_(w), with about 60,000 M_(w) being most preferred.Suitable EVOH polymers for use as components in the compositions of thepresent invention may be obtained from EVAL Company of America under thetradename EVAL® resins. EVOH is also available under the tradenameEvalca® from Kuraray Ltd. and under the tradename Soarnol® from NoltexL.L.C.

Polymers that contain amino groups include polyamides and polyamideresins such as nylon 6, nylon 6/6, nylon 6/12, nylon 12 and poly(amide6-b-ethylene oxide). Polyamide resins are well known in the art andembrace those semi-crystalline and amorphous resins having a weightaverage molecular weight of at least 5,000 and commonly referred to asnylons. The polyamide resin can be produced by condensationpolymerization of equimolar amounts of a saturated dicarboxylic acidcontaining from 4 to 12 carbon atoms with a diamine, in which thediamine contains from 4 to 14 carbon atoms. Excess diamine can beemployed to provide an excess of amine end groups over carboxyl endgroups in the polyamide. Examples of polyamides includepolyhexamethylene adipamide (66 nylon), polyhexamethylene azelaamide (69nylon), polyhexamethylene sebacamide (610 nylon) and polyhexamethylenedodecanoamide (612 nylon), the polyamide produced by ring opening oflactams, i.e. polycaprolactam, polylauric lactam,poly-11-aminoundecanoic acid, andbis(paraaminocyclohexyl)methanedodecanoamide. It is also possible to usepolyamides prepared by the copolymerization of two of the above polymersor terpolymerization of the above polymers or their components, e.g. anadipic, isophthalic acid hexamethylene diamine copolymer.

The third polymer component that is present in the easily processablecomposition is a compatibilizer that is a polar ethylene copolymer. Thecopolymer comprises copolymerized units of ethylene and a comonomerselected from the group consisting of C₄-C₈ unsaturated anhydrides,monoesters of C₄-C₈ unsaturated acids having at least two carboxylicacid groups, diesters of C₄-C₈ unsaturated acids having at least twocarboxylic acid groups and mixtures of such copolymers. Additionally,the ethylene copolymer comprises from about 3 wt. % to about 25 wt. %copolymerized units of the comonomer. The copolymer may be a dipolymeror a higher order copolymer, such as a terpolymer or tetrapolymer.Examples of suitable comonomers of the third polymer component includeunsaturated anhydrides such as maleic anhydride, and itaconic anhydride;C₁-C₂₀ alkyl monoesters of butenedioc acids (e.g. maleic acid, fumaricacid, itaconic acid and citraconic acid), including methyl hydrogenmaleate, ethyl hydrogen maleate, propyl hydrogen fumarate, and2-ethylhexyl hydrogen fumarate; C₁-C₂₀ alkyl diesters of butenedioicacids such as dimethylmaleate, diethylmaleate, and dibutylcitraconate,dioctylmaleate, and di-2-ethylhexylfumarate. Of these, maleic anhydride,ethyl hydrogen maleate and methyl hydrogen maleate are preferred. Maleicanhydride and ethyl hydrogen maleate are most preferred.

Higher order copolymers that are examples of the third polymer componentinclude terpolymers such as ethylene/methyl acrylate/ethyl hydrogenmaleate, ethylene/butyl acrylate/ethyl hydrogen maleate andethylene/octyl acrylate/ethyl hydrogen maleate.

The polar ethylene copolymers act as compatibilizers for the first twopolymeric components, which are dissimilar chemically, i.e. the first isa non-polar polymer and the second is a polar polymer. By compatibilizeris meant that the third component is capable of chemically reacting withthe second component, thereby promoting a strong interface with thefirst and second components which results in improved impact strengthover the uncompatibilized mixture of the first and second components.The ethylene copolymers that are useful in the invention have a ratherhigh level of copolymerized polar monomer (i.e. the monomer selectedfrom the group consisting of C₄-C₈ unsaturated anhydrides, monoesters ofC₄-C₈ unsaturated acids having at least two carboxylic acid groups anddiesters of C₄-C₈ unsaturated acids having at least two carboxylic acidgroups). As a result they have high compatibilizing potential. Thecopolymers are synthesized by random copolymerization of ethylene andthe particular comonomer or comonomers in a high-pressure free radicalautoclave process. Such processes are described in U.S. Pat. No.4,351,931. Direct polymerization eliminates the secondary process stepof grafting which is used to incorporate maleic anhydride into manymaleated polymers. Grafting has been traditionally used to createmaleated compatibilizers, a large number of which are availablecommercially from E. I. du Pont de Nemours and Company, such asFusabond® barrier resins which include polymers such as linear lowdensity polyethylene grafted with maleic anhydride (LLDPE-g-MAH), highdensity polyethylene grafted with maleic anhydride (HDPE-g-MAH), andpolypropylene grafted with maleic anhydride (PP-g-MAH).

The random copolymerization process permits synthesis of polar polymershaving a higher degree of reactivity than the more readily availablegraft copolymers. It is believed that the compatibilizer acts as acoupling agent for the other polymer components of the polymer blend.However, whether it acts as a coupling agent or by some other mode isnot critical in the practice of the present invention. It is preferableto use as little of the compatibilizing material as necessary to obtainthe result desired. Therefore, generally, it is desirable to have ashigh a content of the above-described comonomer as can be obtained, soas to gain the compatibilizing effect with the least amount ofcompatibilizer. In this regard it is preferable that the third polymerincludes at least about 3 wt % copolymerized anhydride, monoester ordiester comonomer, based on the weight of the copolymer. In practice, itis only the process for producing the third polymer that limits theupper limit for incorporation of the comonomer. Preferably, thecomonomer is in the range of greater than about 3 wt. % to about 25 wt.%, based on the weight of the copolymer. More preferably, the comonomeris incorporated into the copolymer in an amount of from about 3.5 wt. %to about 15 wt. %, most preferably in a range of from about 4 wt. % toabout 12.5 wt. %.

The polymer blend compositions that are used in the process of theinvention must contain a rather high level of moisture. It is generallyunderstood in the art that EVOH resins and polyamides should contain lowlevels of moisture for easy processing. For example, it is stated byEVAL Americas in Technical Bulletin No. 100, “Moisture Absorption andDrying of EVAL® Resins”, that “if the moisture content of EVAL® resinsexceeds 0.50%, it should be dried using a circulating hot air dryer.” Inorder for the full compatibilizing potential of the third polymer to berealized in the process of the invention, however, the processablepolymer composition must have an elevated moisture content. This isprovided when water is present in the polymer blend compositioncomprising the first and second polymers at a level of greater than 250ppm, based on the total weight of the first and second polymers. In theprocess of the invention the polymer blend that comprises the first andsecond polymers is combined with the third polymer to form a compositionthat is subjected to high shear mixing in a subsequent step. In orderfor efficient compatibilization, it has been found that it is necessarythat the moisture level be greater than 250 ppm in the polymer blendcomposition of the first and second polymers even though it isrecognized in the art that water often interferes with the reactionbetween anhydride groups and hydroxyl or amine groups. Preferably, thewater content in the polymer blend of the first and second polymers willbe greater than 300 ppm, based on the total weight of the first andsecond polymers.

The above-described first, second and third polymer components arepresent in the easily processable polymer blend in the followingspecified amounts, based on the total weight of the three polymers. Thefirst polymer, i.e. the polyethylene or ethylene alpha-olefin, ispresent in an amount of 55-98 wt. %, preferably 70-95 wt. %. The secondpolymer, i.e. the polymer having hydroxyl or amino groups, is present inan amount of 2-45 wt. %, preferably 5-30 wt. %. The third polymer, i.e.the polar copolymer, is present in an amount of from about 0.1 to about10 weight %, preferably in an amount of from about 0.1 wt % to about 5wt %, more preferably in an amount of from about 1 wt % to about 4 wt %.

A preferred processable composition suitable for use in the process ofthe invention consists essentially of 55-98 wt. %, preferably 70-95 wt.% of the first polymer, 2-45 wt. %, preferably 5-30 wt. % of a secondpolymer having hydroxyl groups, and 0.1-10 wt. % of the polar copolymer,where the weight percentages are based on the total weight of the threepolymers. The water content of the compositions of these preferredcompositions will be as described above. That is, the moisture contentwill be greater than 250 ppm in the composition that consistsessentially of the first polymer and second polymers, based on the totalweight of the first and second polymers. Preferably the water content ofthe polymer blend will be 300 ppm, based on the total weight of thefirst and second polymers prior to mixing the polymer blend with thethird polymer.

The compositions of the present invention can further include optionalmaterials, such as conventional additives used in polymeric materialsincluding plasticizers, stabilizers including viscosity stabilizers andhydrolytic stabilizers, antioxidants, ultraviolet ray absorbers,anti-static agents, dyes, pigments or other coloring agents, inorganicfillers, fire-retardants, lubricants, reinforcing agents such as glassfiber and flakes, foaming or blowing agents, processing aids, antiblockagents, release agents, and/or mixtures thereof. Optional ingredients,when used, can be present in various amounts so long as they are notused in an amount that detracts from the basic characteristics of thecomposition.

Lubricants that are metal salts of higher aliphatic carboxylic acids,where the acids have from 8 to 22 carbon atoms are a particularly usefulclass of optional additives. Such acids include stearic acid, lauricacid, undecanoic acid, palmitic acid and tricosanic acid. The metal ionsinclude sodium, potassium, magnesium, calcium, zinc, barium and aluminumions. Preferred metal ions are zinc and calcium. A preferred salt iszinc stearate. Other preferred salts are calcium or magnesium stearate.It has been found that when at least one of these salts, especially zincstearate, is added to the polymer blend compositions outstanding impactstrength is maintained. Generally, up to about 10 wt. %, based on thetotal weight of the first, second and third polymers, will be present.

Inorganic fillers may also be present. Common fillers include inorganiccompounds, such as minerals and salts. More preferred fillers arecalcium carbonate and talc (Mg₃Si₄O₁₀(OH)₃), and glass fibers. Mostpreferred is glass fibers. The amount of filler that can be added to thecomposition of the present invention is generally up to about 30 weight%, based on the weight of the first, second and third polymers.

Heat stabilizers can optionally be used. Suitable heat stabilizersinclude, for example, a calcium/phosphate derivative of a hinderedphenol sold under the trademark Recyclostab® 411 by Ciba GeigyChemicals. The heat stabilizer compound can also be a compound selectedfrom the group consisting of hydroxyamines, phenols, phosphates andmetal soaps.

Suitable optional antioxidants include alkylated phenols and bis-phenolssuch as hindered phenols, polyphenols, thio and di-thio polyalkylatedphenols, lactones such as 3-arylbenzofuran-2-one and hydroxylamine aswell as Vitamin E.

The above-described processable compositions may be made from virgincomponents or they may be composed of elements from waste streams forrecycling. As such, the blends are easily processable or recyclable dueto the synergistic effect of the combination of polar copolymer andwater.

The process of the invention comprises the steps of providing thepolymer blends that are described above, subjecting them to mixing underhigh shear conditions to form a composite that is a homogeneous blendand recovering the composite. In most cases, this will result in ahighly homogenous blend of the polymers. The process is adaptable forrecycling materials formed of dissimilar polymers, especially thosewherein the components are mixtures of polar and non-polar polymers.

Mixing is preferably accomplished by melt blending under high shearconditions. By high shear conditions is meant that the shear forcespresent are similar to those generated in a co-rotating twin-screwextruder such as those known to practitioners skilled in the art ofcompounding polymer blends. The separate ingredients may be combined asa pellet blend or they may be mixed via simultaneous or separatemetering of the various components. In a recycling process, thecomponents of the waste stream may be treated prior to mixing bygrinding or other processes that comminute or convert the componentsinto particles or small pieces. The components may also be divided andblended in one or more passes into one or more sections of high shearmixing equipment, for example extruders, Banbury mixers, or kneaders.High shear conditions insure that proper dispersion of the componentsoccurs which can promote coupling reactions and formation of acontinuous phase or homogeneous multiple phases.

Generally, extrusion melt blending is preferable for large scaleoperations because it is very economical.

The extruded polymer blends, or composites, are characterized byexcellent Izod impact strength. For example, extruded blends made from99 wt. % of a mixture of 9 wt. % EVOH with 91 wt. % high densitypolyethylene blended with 1 wt. % of a random copolymer of ethylene andmonoethyl maleate where the EVOH and high density polyethylenecomponents contain approximately 700 parts of water before extrusioncompounding have impact strengths in the range of 1070-1230 J/m. Incontrast, similar compositions where a conventional maleic anhydridegrafted resin is used as a compatibilizer have Izod impact strengthsthat are significantly lower.

Once extruded, the composites are recovered and may be formed intoshaped articles by such processes as extrusion or injection molding.Particularly useful articles made by extrusion processes would includetubes, rods, pipes, wire coatings and boards.

Compositions made according to the process of the present invention canbe formed into shaped articles using methods such as injection molding,compression molding, overmolding, or extrusion. Optionally, thecomposites produced by the process can be isolated as particularphysical forms that may be further processed. For example, pellets,slugs, rods, ropes, sheets and molded articles of the present inventionmay be prepared and used for feedstock for subsequent operations, suchas thermoforming operations, in which the article is subjected to heat,pressure and/or other mechanical forces to produce shaped articles.Compression molding is an example of further processing.

While inclusion of certain optional components can be preferred, theexclusion of any optional component can be warranted for any reason.Such reasons can include cost, aesthetics, or any other considerationdeemed important to the practitioner. For example, an optional componentcan be excluded to provide an economic advantage over similar products.

The invention is illustrated by the following embodiments wherein allparts are by weight unless otherwise specified.

EXAMPLES Example 1

A polymer blend composed of 91 parts of a polyethylene having a densityof 0.962 g/cc and a melt index of 1.0 g/10 minutes, sold under the nameof Sclair® 19A polyethylene by Nova Chemicals Corp., and 9 parts of anethylene vinyl alcohol (EVOH) polymer having a melt index of 5.7 g/10minutes and containing 44 mol % vinyl alcohol, sold under the trade nameEVAL E105 resin, was prepared by extrusion compounding using a Werner &Pfleiderer ZSK-30 twin screw extruder having 30 mm screws. All materialswere fed to the extruder at the feed-throat as pellet blends that werepremixed in polymer bags The temperature of the barrel and die weremaintained at 220° C. during the extrusion process. The EVOH polymer hadbeen immersed in water at 23° C. for 24 hours prior to extrusion. Thewater content of three samples of the extruded polymer blend wasdetermined using a Vapor Pro® moisture analyzer and the average valuewas found to be 700 ppm. The polymer blend, in an amount of 99.5 parts,was further blended with 0.5 parts of an ethylene copolymer (dipolymer)having 9 wt. percent copolymerized units of the monoethyl ester ofmaleic acid to form a composite material. The ethylene copolymer wasprepared by a high pressure, free radical copolymerization process.Blending was conducted by extrusion compounding using the same equipmentand conditions employed to prepare the polyethylene/EVOH blend. Physicalproperties of the composite material, measured from injection-moldedspecimens, are shown in Table I. Notched Izod was measured according toASTM D256. Flexural modulus was measured according to ASTM D790. Tensilestrength was measured according to ASTM D638.

Example 2

A sample of the polyethylene/EVOH blend of Example 1, in an amount of99.0 parts, was blended with 1.0 part of the ethylene copolymer ofExample 1 to form a composite material. The same equipment andconditions employed in Example 1 were used. Physical properties of theextruded composite material are shown in Table I.

Comparative Example A

Physical properties of a sample of the polyethylene/EVOH blend ofExample 1 are shown in Table I. This data is designated ComparativeExample A.

Comparative Examples B-D

A sample of the same EVOH polymer that was used in Example 1 was driedat a temperature of 90° C. for 48 hours in a circulating air oven. Asample of 91 parts of the polyethylene of Example 1 was mixed with 9parts of the dried EVOH polymer, using the same equipment and proceduredescribed in Example 1. The physical properties of a sample of theresulting Polymer Blend B are shown in Table I and are designatedComparative Example B. The water content of three samples of the PolymerBlend B was determined using Vapor Pro® moisture analyzer and theaverage value was found to be 100 ppm.

A sample of Polymer Blend B in an amount of 99.5 parts was extrusioncompounded with 0.5 parts of the ethylene copolymer of Example 1 usingthe equipment and procedure of Example 1. Physical properties of theresulting composite are shown in Table I under the designationComparative Example C.

A sample of Polymer Blend B in an amount of 99.0 parts was extrusioncompounded with 1.0 parts of the ethylene copolymer of Example 1 usingthe equipment and procedure of Example 1. Physical properties of theresulting composite are shown in Table I under the designationComparative Example D.

Comparative Examples E

A sample of 99 parts of the polyethylene/EVOH blend of Example 1 wasextrusion compounded with 1 part of an ethylene maleic anhydride graftcopolymer using the same equipment and procedure employed in Example 1.The graft copolymer was a composition that was composed of a highdensity polyethylene (0.96 g/cc) that had been grafted with maleicanhydride. The maleic anhydride content of the graft copolymer was 1 wt.%. Physical properties of the resulting extrusion compounded compositematerial are shown in Table I under the designation Comparative ExampleE.

Comparative Example F

A sample of 99 parts of Polymer Blend B of Comparative Example B wasextrusion compounded with 1 part of the graft copolymer of ComparativeExample E using the same equipment and procedure employed in Example 1.Physical properties of the resulting extrusion compounded compositematerial are shown in Table I under the designation Comparative ExampleF.

TABLE I Sample Example 1 Example 2 Comp. Ex. A Comp. Ex. B Comp. Ex. CComp. Ex. D Comp. Ex. E Comp. Ex. F Tensile Strength 18.8 17.6 13.7 15.417.8 18.1 11.9 15.7 at Break (MPa) Std. Deviation 1.0 0.34 0.52 1.1 0.230.16 3.1 0.79 (MPa) Elongation at 138 154 77 80 49 51 85 56 Break (%)Std. Deviation 25 15 5 5 2 5 13 2 (%) Flexural 1430 1470 1410 1460 14801430 1460 1470 Modulus (MPa) Std. Deviation 76 69 69 83 83 76 55 83(MPa) Notched Izod 1230 1070 320 1010 1120 1020 854 907 Impact Strength(J/m) Std. Deviation 24 100 72 22 52 53 150 46 (J/m) Partial Break 5 5 55 5 5 5 5

1. An easily processable composition prepared by combining: A. a polymerblend comprising
 1. a first polymer selected from the group consistingof polyethylenes and copolymers of ethylene and a C₃-C₁₀ alpha-olefin;and
 2. a second polymer selected from the group consisting of ethylenevinyl alcohol polymers and mixtures of two or more thereof; wherein saidpolymer blend has a moisture content greater than 250 ppm water, basedon the total weight of said first and second polymers; and B. a thirdpolymer that is a polar copolymer produced by a high pressure randomcopolymerization process, said polar copolymer comprising copolymerizedunits of ethylene and from about 3 wt. % to about 25 wt. %, based on theweight of the polar copolymer, of a comonomer selected from the groupconsisting of C₄-C₈ unsaturated anhydrides, monoesters of C₄-C₈unsaturated acids having at least two carboxylic acid groups, diestersof C₄-C₈ unsaturated acids having at least two carboxylic acid groupsand mixtures thereof; wherein said processable composition comprises,based on the total weight of said first, second and third polymers,55-98 wt. % of said first polymer, 2-45 wt. % of said second polymer and0.1-10 wt. % of said third polymer.
 2. A composition of claim 1 whereinsaid first polymer is a polyethylene.
 3. A composition of claim 1wherein said first polymer is a copolymer of ethylene and a C₃-C₁₀alpha-olefin.
 4. A composition of claim 1 wherein said polar copolymercomprises copolymerized units of ethylene and a C₄-C₈ unsaturatedanhydride.
 5. A composition of claim 1 wherein said polar copolymercomprises copolymerized units of ethylene and a monoester of a C₄-C₈unsaturated acid having at least two carboxylic acid groups.
 6. Acomposition of claim 4 wherein said unsaturated anhydride is maleicanhydride.
 7. A composition of claim 5 wherein said monoester is ethylhydrogen maleate.
 8. A composition of claim 1 wherein said polymer blendhas a moisture content of greater than 300 ppm water, based on the totalweight of said first and second polymers.
 9. A composition of claim 1additionally comprising a lubricant.